CN104052338A - Two-step connection of electric motors by means of electromagnetic switches - Google Patents

Abstract

A method and apparatus using electromagnetic switching in a two-step connection process is provided to minimize surge currents and torque oscillations in three-phase motors during starts.

Description

By means of electromagnetic switch, two steps of motor are connected

Technical field

Present disclosure relates generally to control, protection and the starting of threephase motor and driving arrangement, more specifically, relates to by means of electromagnetic switch two steps of motor are connected.

Background technology

Most threephase motor starters is to use the simple device of contactor of all phases that substantially connects simultaneously and be cut to the three phase mains of motor.In the time of this three phase mains, application causes having by excessive, potential peak value surge current and a torque pulsation that destructive stress puts on power distribution network, motor and drives load.These surge currents add normal starting current (in-rush current), and can damage the electrical contacts using in starter contactor and the life-span that shortens starter.The tripping operation of looking genuine (nuisance trip) causing for fear of the more high peak current owing to causing because of these surge currents, common way is that the break opening contact of the circuit-breaker in power distribution network (trip level) is arranged than supporting that the required break opening contact of nominal load is higher.This has reduced the ability that minimizes infringement in the situation that circuit breaker nonserviceables.Although exist the starting motor reduce or eliminate these negative attributes alternative method (such as, motor driver and Electronic Soft Starter), but these alternative schemes are conventionally more large-scale, more expensive, more complicated for installing and configuring, and have the useful life shorter than dynamo-electric starter.

Summary of the invention

Embodiment comprises electromagnetic switch, and this electromagnetic switch provides and causes some windings of motor before the remainder experience current flowing of winding, to experience two step connection procedures of current flowing.Two so possible embodiment that provide two steps to switch have been described.An embodiment is used single-pole switch (SPS).Another embodiment is used the delay utmost point contactor (DPC) that comprises three utmost points, and one of them utmost point is designed to temporal skew, come closed with respect to the closure of two other utmost point.At present, although other devices of operation that can control switch are also satisfactory, these two embodiment are used the DC(direct current of being controlled by electronic installation) electromagnet.

Accompanying drawing explanation

In order more completely to understand present disclosure and advantage thereof, now with reference to the detailed description of carrying out below in conjunction with accompanying drawing, wherein identical Reference numeral represents identical parts, in the accompanying drawings:

Fig. 1 shows motor branch circuit assembly;

Fig. 2 shows assembly, and this figure is used three utmost points to postpone the outside drawing of the embodiment of utmost point contactor (DPC);

Fig. 3 shows the cross section of the assembly of Fig. 2;

Fig. 4 shows another cross section of the assembly of Fig. 2;

Fig. 5 and Fig. 6 show the operation of the center pole of assembly;

Fig. 7 and Fig. 8 show the operation of the outer utmost point of assembly;

Fig. 9 and Figure 10 show the closed and disconnected timing sequence for assembly;

Figure 11 shows assembly, and this figure is the outside drawing that uses the embodiment of single-pole switch (SPS);

Figure 12 shows the cross section of the assembly of Figure 11;

Figure 13 shows another cross section of the assembly of Figure 11;

Figure 14 shows and describes three phase mains to be connected to the curve chart that triangle connects the effect of motor simultaneously;

Figure 15 shows and describes three phase mains two steps to be connected to the time-sequence curve chart that triangle connects the effect of motor;

Figure 16 shows for one group of example with the motor of Y shape configuration and connects;

The vectogram of closure when Figure 17 shows for all contactor utmost points;

Figure 18 shows the vectogram for two steps connections of the contactor utmost point;

Six three of may connect sequential that Figure 19 shows for two step closures of the motor of Y shape configuration connect phase voltage waveform regularly;

Figure 20 shows the motor having in the triangular configuration of the outside contactor utmost point connecting of motor winding;

Figure 21 shows the motor of the triangular configuration of the contactor utmost point with motor winding inside;

Figure 22 shows for the motor of triangular configuration of the contactor utmost point with motor winding inside with the sequential chart of the first step of 60 electric degree closures;

Figure 23 shows the closed sequential chart of each contactor utmost point for two step startings of the motor of Y shape configuration;

Figure 24 shows and uses three utmost points to postpone the motor circuit of utmost point contactor (DPC);

Figure 25 shows the motor circuit that uses single-pole switch (SPS).

Embodiment

When electromagnetic contactor is used for from static started induction motor, according to the size of motor and structure, motor draws the starting current between six times and ten times of motor FLA (FLC) from power supply conventionally.Along with motor approaches at full speed, this electric current drop to motor on the smaller value that matches of load.

Yet, during power supply is connected to motor simultaneously, also there will be many less desirable phenomenons.Have the serious vibration pulsation of the torque of motor generation, it can continue to reach the several seconds in larger motor.This reaction force by experience is forced at whole drive system (especially forcing at shaft coupling, gear box, bearing and stator winding) by high mechanical stress.The peak value of pulsating torque both can be positive also can bear, and can be many times of the breakdown torque of experience under normal operation.This pulsating torque is the key factor that causes fault (particularly motor suffers Fraquent start).

Same serious, during the transient period of torque pulsation, source current peak value can surpass the twice of the stable state locked rotor starting current of expection.This abnormal high electric current is called as surge current, and can cause the problem for motor protection.Conventionally, motor starter combines contactor at motor, to draw the situation incision power-off motivation of multiple current with overload protection.Overload mechanism must allow high surge current and not prematurely cut off motor, and however, overload mechanism must be in the situation that motor becomes transships and draw more than 110% full-load current only and close motor at run duration.For high-efficiency electric motor, surge current can reach 18/20 times of FLC, and this makes arranging of overload relay and circuit breaker complicated to allow starting and enough running protections are still provided.

Yet, can by revise the mode that power supply is connected to motor greatly reduce or eliminate torque pulsation and surge current the two.If be extremely connected threephase motor by being placed on power supply with the contactor between Terminal of motor, and operate this threephase motor and later connect remaining phase so that first connect two phases (when the line voltage distribution between these two phases has peak value) and 1/4th the supply voltage cycle, greatly reduce or eliminated torque pulsation and surge current the two.

When induction motor is static, the back electromotive force (back emf) generating in inside is zero.If ignore stator resistance R _s,, when applied power source, according to stator inductance, determine current flowing.If all three phases are energized together, current flowing is by mobile balance stable state three-phase AC(is exchanged) starting current adds that the DC transient current in every exponential damping existing with difference amount in mutually forms.When all electric currents are all zero and its rate of change while being subject to motor inductance restriction, connecting the amplitude of constantly determining DC transition.In the moment after immediately connecting, motor current is still zero.Therefore, now, steady-state current comes associated with DC transient current by following formula:

Steady-state current+DC transient current=0

As shown in formula, in the moment after immediately connecting, the amplitude of DC transient current is equal with stable state starting current value and symbol is contrary.This DC direct current is decayed along with motor magnetizing time constant.

The impact of DC electric current is the serious torque pulsation that causes following motor starting.Because DC field component other, irrotational and decay has been introduced in DC transition like this, rather than the stable state AC electric current Rotating with Uniform magnetic field that can produce.When they are calibrated (aligned), add AC field to, but along with stator field moves and do not calibrate with DC field component, from AC field, deduct.Therefore, motor flux is vibrated between (AC magnetic flux+DC magnetic flux) and (AC magnetic flux-DC magnetic flux), rather than keeps stable (rotation) value.This causes motor torque seriously vibration under supply frequency, and this vibration only weakens along with DC flux decay.This may continue the several seconds in larger motor.

Two step connection procedures can be eliminated the surge causing due to the excitation DC magnetic transient current of slow-decay and the torque pulsation that is associated.The motor connecting for Y shape, first by two of motor, be connected to power supply terminal to strengthen electric current in two motor windings, so that in the moment that connects residue phase, all three electric currents all just in time equal its stable state AC value corresponding with all points that are finally connected to mutually power supply wave shape.If immediately before or after connecting third phase, electric current has steady-state value, do not generate additional DC transient current, motor starts to equal one group of balance AC electric current of stable state locked-rotor current, and does not have torque pulsation.

When from static starting motor, must select connect the point in the first two phase time power supply wave shape, so that these intensifying currents in are mutually just in time to reach in the required steady-state value of the moment that connects the 3rd power supply phase.Because most of threephase motors have the winding impedance much larger than its winding resistance, therefore in the time of can thering is peak value by the line voltage distribution when between two power supplys phases, these two power supplys are connected to motor and roughly realize this result, and about 90 degree (1/4th power cycles) connect remaining phase later.

Fig. 1 shows motor branch circuit assembly 100.Motor branch circuit assembly 100 comprises motor, has the line voltage distribution facies unit 59 of phase A, phase B and phase C, motor contactor 3 and overload relay 4.For the disclosed embodiments, with postponing utmost point contactor (DPC) or three independent single-pole switchs (SPS), replace motor contactor 3.

Fig. 2 shows assembly 200, and this figure is the outside drawing of an embodiment of three utmost point DPC.Assembly 200 comprises that shell 5, composite type termination and fixed contact 6, the molded portion 7 of moving contact portion carrier and screw are fastened to the attachment point 8 in assembly 200 by wire.

Fig. 3 shows assembly 200 along the cross section of line A-A.In assembly 200, while there is closure, provide spring 10, the moving contact portion 9 of contact.Ferromagnet frame 11 supports the magnet face 12 coordinating with armature 13.Coil 14 produces magnetic flux, and when coil 14 is de-energized, spring 15 promotes actuating assembly away from magnet face 12.The molded portion 7 of moving contact portion carrier is physically attached to armature 13 so that they move together.Meanwhile, parts 7, parts 11, parts 12, parts 13, parts 14 and parts 15 comprise actuating assembly.

Fig. 4 shows assembly 200 along the cross section of line B-B, and this cross section shows the molded portion 7 of moving contact portion carrier with the center pole 18 closed after a while apart from x that had two identical outer utmost points 16 of DPC and the outer utmost point 17 and physical deflection.Spring 19 is for generation of contact site clossing pressure.Sheet spring 20 in the utmost point 16 and the utmost point 17 is for producing initial contact when the closure.Even if sheet spring 20 provides improved performance, same suitable, in different embodiment, eliminate these sheet springs and only with spring, produce initial contact or replace them with other compressible materials or own product.In being designed to advance than other utmost points more at a distance extremely, can also omit these sheet springs.

Fig. 5 and Fig. 6 show the operation of center pole 18.In Fig. 5, the center pole 18 in open position has the distance x that approximates greatly in Fig. 4 and the contact gap g of the contact gap h sum in Fig. 6.In Fig. 6, center pole 18 has less contact gap h.This position is by obtaining towards magnet face 12 forward pitch actuating assembly from x.

Fig. 7 and Fig. 8 show the operation of the outer utmost point 16 or the outer utmost point 17.In Fig. 7, the outer utmost point 16 or the outer utmost point 17 do not have in compressed situation in the open position with contact site 6 distance f at sheet spring 20.Sheet spring 20 has the degree of depth of distance y.In Fig. 8, the outer utmost point 16 or the outer utmost point 17 are in the close position in the compressed situation of sheet spring 20.This position is by obtaining towards magnet face 12 forward pitch actuating assembly from f+y.

Fig. 9 and Figure 10 show respectively the closed timing sequence of DPC and disconnect timing sequence.At period of contact, the outer utmost point 16 and the outer utmost point 17 be closure and center pole 18 closure after 90 electric degrees under peak line voltage.At off period, center pole 18 under zero line current, disconnect and the outer utmost point 16 and the outer utmost point 17 at 90 electric degrees later disconnection.

Figure 11 shows the assembly 400 that comprises single-pole switch (SPS).Assembly 400 comprises shell 20, composite type termination and fixed contact 6, the extension of the molded portion 21 of moving contact portion carrier and the attachment point 8 of fastened by screw wire and motor cable.

Figure 12 shows assembly 400 along the cross section of line AA-AA.Assembly 400 comprises moving contact portion 9 and the spring 10 of contact is provided when closure.Ferromagnet frame 11 supports the magnet face 12 coordinating with armature 13.Coil 14 excitation ferromagnet framves 11 and spring 15 for opening magnet face 12 when coil 14 is de-energized.

Figure 13 shows assembly 400 along the cross section of line BB-BB.Assembly 400 comprises the molded portion 21 of moving contact portion carrier with spring 19, the pressure that spring 19 is determined between moving contact portion 9 and fixed contact 6.

connect the example being connected with two steps simultaneously

Figure 14 shows and describes three phase mains to be connected to the time-sequence curve chart that triangle connects the effect of motor simultaneously.Curve has been described the starting of triangle motor unloaded in the situation of the closed contactor utmost point at the same time.Bottom trace illustrates serious torque pulsation, and middle trace illustrates very unbalanced three-phase line electric current.Top trace illustrates and connects supply voltage constantly.

Figure 15 shows and describes three phase mains two steps to be connected to the time-sequence curve chart that identical triangle connects the effect of motor.Along with peak current significantly reduces, the motor power electric current of almost having eliminated torque pulsation and balance.Top voltage curve shows two steps and connects timing sequence.

the principle that two steps connect

Following part set forth the principle of two step connection procedures and can how to use postpone utmost point contactor (DPC) or single-pole switch by the application of principle of this two steps connection procedure to the motor of Y shape configuration and the motor of triangular configuration.One group of example that Figure 16 shows the motor with Y shape configuration connects.The utmost point 1,2 and 3 of contactor can be placed on each end of winding.

due to the DC transition of switching three power phases and causing simultaneously

The space vector that three-phase mains voltage ABC can provide by following formula describe:

${\stackrel{\‾}{u}}_S\left(t\right)=u_S{e}^{j(\mathrm{wt}+\mathrm{\α})}---\left(1\right)$

Wherein, u _sfor power supply phase voltage amplitude, space vector angular frequency with power supply is rotated, and α for when applying electric power at the power supply phase angle of time t=0.

According to Faraday's law, by following formula, provide the magnetic flux of motor enhancing:

$\frac{d\stackrel{\‾}{\mathrm{\ψ}}}{\mathrm{dt}}={\stackrel{\‾}{u}}_S\left(t\right)=u_S{e}^{\mathrm{jwt}}{e}^{\mathrm{\α}}---\left(2\right)$

By integration,

$\begin{array}{c}\stackrel{\‾}{\mathrm{\ψ}}\left(t\right)=u_S\frac{e^{\mathrm{jwt}}}{\mathrm{j\ω}}{e}^{\mathrm{j\α}}+{\stackrel{\‾}{\mathrm{\ψ}}}_{\mathrm{DC}}\\ ={\stackrel{\‾}{\mathrm{\ψ}}\left(t\right)}_{\mathrm{Steady\; state}}+{\stackrel{\‾}{\mathrm{\ψ}}}_{\mathrm{DC\; transient}}\end{array}---\left(3\right)$

Wherein, to meet the required integration constant of initial condition.When at t=0 with phase angle α, in motor, not having will in the situation of magnetic flux (that is, ψ=0) while being applied to motor:

$\stackrel{\‾}{\mathrm{\ψ}}\left(0\right)=0=u_S\frac{e^{\mathrm{j\α}}}{\mathrm{j\ω}}+{\stackrel{\‾}{\mathrm{\ψ}}}_{\mathrm{DC}}---\left(4\right)$

Therefore, DC transition magnetic flux is provided by following formula:

${\stackrel{\‾}{\mathrm{\ψ}}}_{\mathrm{DC}}=-u_S\frac{e^{\mathrm{j\α}}}{\mathrm{j\ω}}=j\frac{{\stackrel{\‾}{u}}_S\left(0\right)}{\mathrm{j\ω}}---\left(5\right)$

Make the general solution of this magnetic flux be:

$\begin{array}{c}\stackrel{\‾}{\mathrm{\ψ}}\left(t\right)=-j\frac{{\stackrel{\‾}{u}}_S\left(t\right)}{\mathrm{\ω}}+j\frac{{\stackrel{\‾}{u}}_S\left(0\right)}{\mathrm{\ω}}\\ ={\stackrel{\‾}{\mathrm{\ψ}}\left(t\right)}_{\mathrm{Steady\; state}}+{\stackrel{\‾}{\mathrm{\ψ}}}_{\mathrm{DC\; transient}}\end{array}---\left(6\right)$

In equation (6), the factor-j is multiplied by voltage space vector mean stable state magnetic flux along with be rotated but lag behind when rotated 90 °.On the other hand, DC transition magnetic flux when connecting, be fixed on primary power vector 90 °, direction the place ahead orientation on and only gradually decay.Figure 17 shows the space vector of the relation of performance equation (3), (5) and (6).Stable state magnetic flux there is constant amplitude and around according to the transition magnetic flux of slow-decay only definite fixed center is rotated.Therefore, along with rotation, DC magnetic flux existence cause resultant flux amplitude strongly vibrate.Effect is strong torque pulsation and the unbalanced electric current before DC transition decay.

with two step connection procedures, greatly reduce or eliminate DC transition

If carry out power supply connection procedure with two steps, can greatly reduce or eliminate DC transition.Although the embodiment of different motor combination has described the use of particular power source phase below, any combination of power supply phase that connects the identical sequential of maintenances and voltage characteristic for two following steps is all applicable equally.In fact, described two steps connect and cause the operation of other electric current inflow motor relevant.Same being applicable to,, any time before these steps connects a phase of motor, as long as this does not cause electric current inflow motor.When under these circumstances, electric current only can be connected to power supply at the second-phase of motor, flow and be equal to and connect two phases simultaneously.

step 1

Figure 18 shows the vectogram of two steps connections of the contactor utmost point.At time t=0, at least one motor winding, the power supply of the mobile required minimum number of generation current is connected to motor.Time t=0 represents calculated in order to produce the time that makes when producing very little DC transition or not producing DC transition can closed residue phase (in step 2) required condition.Current flowing by motor winding has strengthened the magnetic flux in direction as shown in figure 18

step 2

When by space vector during the directed β of the power supply space vector of describing in Figure 18, remaining power supply is connected to motor.Now, all three power supplys are all connected mutually, and the initial magnetic flux that strengthens in step 1 of voltage space vector sum corresponding to correct steady-state value without any need for additional DC magnetic flux transition with 90 °, to lag behind voltage space vector when connecting power supply phase A stable state magnetic flux in the instantaneous position of directed β initial value.After this, voltage and magnetic flux under its stable state, be separated by 90 ° of synchronous rotaries and there is no torque pulsation or too high peak current.

motor applications two steps to Y shape configuration connect

The dq component that is applied to the voltage space vector of motor is taken as:

$\begin{array}{c}{u}_{\mathrm{SD}}=2/3(u_{\mathrm{SA}}-{0.5u}_{\mathrm{SB}}-{0.5u}_{\mathrm{SC}})\\ u_{\mathrm{SQ}}=1/\sqrt{3}(u_{\mathrm{SB}}-u_{\mathrm{SC}})\end{array}---\left(7\right)$

Wherein, u _sA, u _sB, u _sCthe voltage at three winding two ends.According to the amplitude u of power supply phase voltage _s, by following formula, provide CB line voltage distribution:

$u_{\mathrm{CB}}=\sqrt{3}{u}_S\sin (\mathrm{\ωt}+\mathrm{\α})---\left(8\right)$

Suppose as line voltage distribution u _cBwhile thering is peak value, connect power supply phase B and C and in the setup times t=0 of this some place, α=270 °.When only connecting B-source voltage and c-power supply voltage and A phase winding and still cut off, line voltage distribution is divided equally at B winding and C winding two ends, and winding voltage is provided by following formula:

$u_{\mathrm{SB}}=-1/2u_{\mathrm{BC}},u_{\mathrm{SC}}=1/2u_{\mathrm{BC}},u_{\mathrm{SA}}=0---\left(9\right)$

Use equation (7), dq component is:

u _SD＝0，u _SQ＝-u _S (10)

And in whole period β, u _sDremain zero.Therefore,, during 90 ° of interval β before connecting phase A, we obtain:

$\frac{{\mathrm{d\ψ}}_Q}{\mathrm{dt}}=u_{\mathrm{SQ}}=-u_S\sin (\mathrm{\ωt}+\mathrm{\α}),\frac{{\mathrm{d\ψ}}_D}{\mathrm{dt}}=u_{\mathrm{SD}}=0---\left(11\right)$

In the β of interval, carry out integration to obtain the magnetic flux providing as follows:

${\mathrm{\ψ}}_Q=-u_S\underset{\mathrm{\ωt}=0}{\overset{\mathrm{\ωt}=\mathrm{\π}/2}{\∫}}\sin (\mathrm{\ωt}+\mathrm{\α})\mathrm{dt}---\left(12\right)$

While making to connect phase A when at ω t=β=pi/2:

${\mathrm{\ψ}}_D=0,{\mathrm{\ψ}}_Q=-\frac{u_S}{\mathrm{\ω}}---\left(13\right)$

$\stackrel{\‾}{\mathrm{\ψ}}\left(\mathrm{\β}\right)=-j\frac{u_S}{\mathrm{\ω}}---\left(14\right)$

This is making it possible in the situation that the instantaneous steady-state value of starting without any DC transition magnetic flux and the torque pulsation being associated and the limiting current peak value of decay shown in Figure 18 just

Figure 19 shows phase voltage waveform, and it illustrates six three of may connect sequential for two step closures of the motor of Y shape configuration.Vertical line represents that at least one phase that connects power supply when expection is so that the time that the current flowing in motor winding increases.The delay being represented by β represent to cause first of current flowing in motor connect with cause power supply be allly connected to the period of second of motor between being connected.

motor applications two steps of diabolo configuration connect (connection outside triangle)

Figure 20 illustrates the motor of triangular configuration, and it has at the outside contactor utmost point connecting of motor winding.When connecting the motor of triangular configuration with two step connection procedures, if the contactor utmost point is outside at triangle, by closed two utmost points and connect two phases at its circuit amplitude peak, about the motor of Y shape configuration, connect, as shown in figure 20.Then, by the closed utmost point 3,90, connect residue phase after spending.In Figure 20, phase A and phase C are two phases that are first closed, and are then phase B.Calculate now the magnetic flux strengthening.CA line voltage distribution is:

$u_{\mathrm{CA}}=\sqrt{3}{u}_S\sin (\mathrm{\ωt}+\mathrm{\π}/2)---\left(15\right)$

And when at moment t=0, connect CA phase time, CA line voltage distribution equals its crest voltage owing to there not being the connection of B phase, therefore the voltage at three winding two ends is provided by following formula:

$\begin{array}{c}{u}_{\mathrm{SA}}=\sqrt{3}{u}_S\sin (\mathrm{\ωt}+\mathrm{\π}/2)\\ u_{\mathrm{SB}}=\sqrt{3}/2u_S\sin (\mathrm{\ωt}+\mathrm{\π}/2)\\ u_{\mathrm{SC}}=u_{\mathrm{SB}}\end{array}---\left(16\right)$

Therefore, use dq voltage equation (7):

$\begin{array}{c}{u}_{\mathrm{SD}}=\sqrt{3}{u}_S\\ u_{\mathrm{SQ}}=0\end{array}---\left(17\right)$

Before phase B is connected, 90, spends in the period strengthened magnetic flux carried out integration and drawn:

${\mathrm{\ψ}}_{\mathrm{SD}}=\underset{0}{\overset{\mathrm{\ωt}=\mathrm{\π}/2}{\∫}}{u}_{\mathrm{SD}}\mathrm{dt}=\sqrt{3}{u}_S\underset{0}{\overset{\mathrm{\ωwt}=\mathrm{\π}/2}{\∫}}\sin (\mathrm{\ωt}+\mathrm{\π}/2)\mathrm{dt}=\sqrt{3}{u}_S/\mathrm{\ω}---\left(18\right)$

This is to make in the situation that can start required instantaneous steady-state value without any the DC transition of decay ${\stackrel{\‾}{\mathrm{\ψ}}}_0.$

motor applications two steps of diabolo configuration connect (connection in triangle)

Figure 21 shows the motor of triangular configuration, and wherein the contactor utmost point is in motor winding.As shown in figure 21, if be placed on (conventionally like this for the starting of Y shape-triangle) in triangle for the contactor utmost point of triangle operation, can realize the current flowing at least one winding by being connected to power supply by one of motor.In Figure 21, when the utmost point 1 is connected to phase c-power supply by the switch sides of winding A, electric current flows into winding A.

Figure 22 illustrates the modification sequential chart of first step, and wherein in the situation that the contactor utmost point is in motor winding, the motor for triangular configuration is closed at 60 electric degrees.Owing to not having electric current to flow into B winding and C winding, therefore must be with line voltage distribution u _cAmore long duration β=120 ° of 60 ° of phase angles starting in strengthen magnetic flux, rather than in period β=90 with voltage max starting °.

There is the line voltage distribution u applying at A winding two ends in Figure 21 _cAwinding voltage by following formula, provide:

$u_{\mathrm{SA}}=\sqrt{3}{u}_S\sin \mathrm{\ωt},u_{\mathrm{SB}}=0,u_{\mathrm{SC}}=0---\left(19\right)$

According to equation (7), dq space vector voltage provides by following formula:

$\begin{array}{c}{u}_{\mathrm{SD}}=\frac{2}{3}\sqrt{3}{u}_S\sin \mathrm{\ωt}\\ u_{\mathrm{SQ}}=0\end{array}---\left(20\right)$

Therefore,, by carry out integration in period β, magnetic flux becomes:

${\mathrm{\ψ}}_{\mathrm{SD}}=\underset{\mathrm{\π}/3}{\overset{\mathrm{\π}}{\∫}}{u}_{\mathrm{SD}}\mathrm{dt}=\sqrt{3}\frac{u_S}{\mathrm{\ω}}---\left(21\right)$

ψ _SQ＝0 (22)

This is suitable magnetic flux and orientation, this magnetic flux and directed make the contactor utmost point 2 and the utmost point 3 the zero crossing place of CA line voltage distribution closure with full voltage is applied to motor all windings and without any DC transition.

use single-pole switch (SPS) to carry out two step connections

Single-pole switch has the electromagnet of DC operation, and wherein electronic coil control operation is according to single group fixed contact and moving contact portion in the single shell of Figure 11 and Figure 12.Armature 13 in Figure 12 works to control connection and the cut-out of contact site 6 and contact site 9 by the magnetic field being produced by electromagnet coils 14.Three motor as described previously connect described in configurations, and these contact sites are used for each of power supply to be connected to motor.Because their allow each of power supply to carry out independent control to the connection of motor mutually, therefore, they are applicable to two step closing course very much.

use SPS should to the motor of the motor of Y shape configuration and triangular configuration (outside connection) by two steps, connect

In order to start the motor of Y shape configuration as shown in figure 16 or the motor of triangular configuration as shown in figure 20 with two step connection procedures, three contactor utmost points 1,2 and 3 must the desired point on power supply wave shape be sentenced correct closing in sequence.For the first step of process, two extremely must be connected to power supply by motor, so that first electric current starts to flow at least one motor winding under crest voltage amplitude (about 90 degree between two circuits that are connected mutually after zero crossing).This can connect by this point on power supply wave shape two utmost points simultaneously or extremely realize by a closed utmost point of the time early and closed another of this point on power supply wave shape.Two kinds of modes are all applicable equally, but can prove rear a kind of more easily realization.Should be on power supply wave shape about 90 spend after the closed remaining utmost point.

use SPS diabolo configuration (connection in triangle) motor applications two steps to connect

In order to start the motor of triangular configuration as shown in figure 20 with two step connection procedures, the desired point that three contactor utmost points 1,2 and 3 must be on power supply wave shape is with correct closing in sequence.For the first step of process, one extremely must be connected to power supply by motor, so that first electric current starts to flow into a motor winding in the 30 point places of spending (60 after zero crossing spent about between two circuits that are connected mutually greatly) before crest voltage amplitude.Should be on power supply wave shape about 120 spend after closed remaining two utmost points.

the control connection time

In order to meet the required sequential of two step connection procedures, must know the contact site closing time of SPS.This contact site closing time represents from excitation SPS magnetic coil until contact site makes electric current can flow to from power supply the time of motor.This information can obtain by the feature that is designed to after making contact site conventionally.

Also need to know that supply frequency and zero crossing are constantly.For this purpose, we believe at present, use the known method of the phase-locked loop based on software (PLL) of synchronizeing with the supply voltage zero crossing of one or more power supply phases to be the most easily to realize and to be best.Yet, existing for determining supply frequency and zero crossing many methods constantly, these methods are applicable equally and in the situation that such as other features of voltage monitoring and power phase row, also from the device of monitoring voltage, to obtain can be preferred.

By monitoring power supply and know the contact site closing time of SPS, can calculate the time of each SPS coil of excitation, so that the desired point place being connected on power supply wave shape between power supply and motor occurs.For calculating a kind of embodiment of the formula of these coil stimulatings time, can be:

t _CE＝t _ZC+d _OffsetXt _Degree-t _CC

Wherein, t _cEfor wanting the time of excitation coil, t _zCfor estimated time will based on the zero crossing time, d _offsetfor expectation by power supply be connected to motor, power supply wave shape is from t _zCthe drift rate rising, t _degreethe time period equating with one of power supply wave shape degree, and t _cCit is the time period while making electric current to flow to motor from power supply to contact site during from excitation SPS coil.

use two steps that postpone utmost point contactor (DPC) to connect

In realizing two step connection procedures, to the alternative of single-pole switch, be delay utmost point contactor.This design is to have the triple pole contactor that is arranged to carry out with preferred angle for two step connection procedures the contact site of Close asynchronously.Center pole is magnetically arranged to more closed than the outer utmost point.

For contact site is closed, moving contact portion carrier has the contact site spring that the contact site to being assembled in utmost point window operates.Central authorities' contact site by make central window young amount x and being offset with respect to the contact site of two outer utmost points.Using identical contact site and revising molded contact site carrier causes the outer utmost point as early closed in expectation.Control contactor electromagnet is to stop (stall) in a position of this interim step.

In closed step 1, the contact site gap h of center pole has enough dielectric strengths to avoid conducting within about 1/4th primary period after the contact site closure of the utmost point outside two.According to the size of contactor, this gap h is generally 0.5mm to 1mm.

To entering the electric power of contactor operating coil, control, so that be combined with central contact site physical deflection and other contactor power to equaling in period of 90 electric degrees of supply frequency outer extremely closure in this stop position.

Then, to entering the electric power of contactor operating coil, adjust, so that surpass apart from d at all contact site spring-compresseds in extremely, thereby DPC is placed into its final make position.

Alternatively, the shorter delay of approximately 1 second with realize stable after, the electric power that enters contactor operating coil is reduced to the level that is enough to contactor to remain on make position.

Figure 24 illustrates the motor circuit that uses three utmost points delay utmost point contactors (DPC), and Figure 25 illustrates the motor circuit that uses single-pole switch (SPS).In each motor circuit, switch 53 is coupled to controller 50.Controller 50 is adjusted to the electric power of the associated actuators assembly of corresponding contact device, to connect to make contact site to engage or depart from according to two steps.When aligning the electric power applying and regulate, controller 50 operates explicitly with voltage over zero monitor.

Although describe the disclosure in detail with reference to specific embodiment, it should be understood that, those skilled in the art can determine various other change, substitute, modification, change and modification, and the disclosure comprises all such change in the spirit and scope that fall into claims, substitutes, modification, change and modification.In addition the disclosure any statement restriction that be not intended to be subject to by any way do not reflect in claims in addition, in specification.

Claims (20)

1. a method of switching electrical contacts, comprising:

Monitor the voltage in the electrical system with power supply and motor;

The first phase angle place after phase voltage zero crossing or before closed the first direct solenoid control contact site, so that electric current at least one winding roughly the first phase angle place after described phase voltage zero crossing start to flow, described direct solenoid is controlled contact site and is configured to regulate the electric power that is fed to described motor by described power supply; And

After this, constantly, closed remaining direct solenoid is controlled contact site to the regulation after described the first direct solenoid is controlled contact site closure.

2. method according to claim 1, wherein, described regulation is the second phase angle with respect to the voltage in the measured described system of described the first phase angle constantly.

3. method according to claim 2, wherein, when described motor winding has Y shape configuration, described the first phase angle is approximately 60 degree and described the second phase angle is approximately 90 degree.

4. method according to claim 2, wherein, when described motor winding has triangular configuration and described direct solenoid and controls contact site carrying for the electric current of a more than motor winding, described the first phase angle is approximately 60 degree and described the second phase angle is approximately 90 degree.

5. method according to claim 2, wherein, when described motor winding has triangular configuration and described direct solenoid and controls contact site carrying for the electric current of a motor winding, described the first phase angle is approximately 30 degree and described the second phase angle is approximately 120 degree.

6. a contactor assembly, comprising:

A plurality of independent direct current Electromagnetic Control contact sites;

For carry out the device of monitoring voltage zero crossing at least one electric power applying to described a plurality of independent direct current Electromagnetic Control contact sites; And

Controller, can with device and the described a plurality of independent direct current Electromagnetic Control contact site operations associated for monitoring voltage zero crossing, and be configured to when described controller receives closed circuit command signal, engage less than all described a plurality of independent direct current Electromagnetic Control contact sites.

7. contactor assembly according to claim 6, wherein, described a plurality of independent direct current Electromagnetic Control contact sites comprise at least one independent direct current Electromagnetic Control contact site mutually for each of polyphase source.

8. contactor assembly according to claim 7, wherein, described controller is only also configured to, after engaging less than all described a plurality of independent direct current Electromagnetic Control contact sites, to engage and to reach described a plurality of independent direct current Electromagnetic Control contact site.

9. contactor assembly according to claim 8, wherein, described controller is only also configured to, after joint reaches described a plurality of independent direct current Electromagnetic Control contact site, to depart from and to reach described a plurality of independent direct current Electromagnetic Control contact site.

10. contactor assembly according to claim 9, wherein, described controller is only also configured to, after disengaging reaches described a plurality of independent direct current Electromagnetic Control contact site, to engage less than all described a plurality of independent direct current Electromagnetic Control contact sites.

11. contactor assemblies according to claim 10, wherein, described controller is only also configured to, after engaging less than all described a plurality of independent direct current Electromagnetic Control contact sites, to engage and to reach described a plurality of independent direct current Electromagnetic Control contact site.

12. contactor assemblies according to claim 8, wherein, described controller is also configured to engage less than all described a plurality of independent direct current Electromagnetic Control contact sites, so that these independent direct current Electromagnetic Control contact sites are used two step connection procedures three phase mains to be connected to the threephase motor winding with Y shape configuration.

13. contactor assemblies according to claim 8, wherein, described controller is also configured to engage less than all described a plurality of independent direct current Electromagnetic Control contact sites, so that these independent direct current Electromagnetic Control contact sites are used two step connection procedures three phase mains to be connected to the threephase motor winding with triangular configuration.

14. contactor assemblies according to claim 11, wherein, described controller is only also configured to engage less than all described a plurality of independent direct current Electromagnetic Control contact sites so that these independent direct current Electromagnetic Control contact sites are used after two step connection procedures are connected to the threephase motor winding with Y shape configuration by described three phase mains, only after disengaging reaches described a plurality of independent direct current Electromagnetic Control contact site, joint is less than all described a plurality of independent direct current Electromagnetic Control contact sites, so that these independent direct current Electromagnetic Control contact sites are used two step connection procedures three phase mains to be connected to the threephase motor winding with triangular configuration.

15. 1 kinds of methods of switching electrical contacts, comprising:

Detection has the voltage in the electrical system of power supply and motor;

The first phase angle place after phase voltage zero crossing or before closed the first direct solenoid control contact site, so that electric current at least one winding roughly the first phase angle place after described phase voltage zero crossing start to flow, described direct solenoid is controlled contact site and is configured to regulate the electric power that is fed to described motor by described power supply; And

After this, constantly, closed the second direct solenoid controls contact site and the 3rd direct solenoid is controlled contact site for the regulation after described the first direct solenoid is controlled contact site closure;

Wherein, when described motor winding has Y shape configuration, described the first phase angle is approximately 60 degree and described the second phase angle is approximately 90 degree.

16. methods according to claim 15, wherein, when described motor winding has triangular configuration and described direct solenoid and controls contact site carrying for the electric current of a more than motor winding, described the first phase angle is approximately 60 degree and described the second phase angle is approximately 90 degree.

17. methods according to claim 15, wherein, when described motor winding is when triangular configuration and described direct solenoid are controlled contact site carrying for the electric current of a motor winding, described the first phase angle is approximately 30 degree and described the second phase angle is approximately 120 degree.

18. methods according to claim 15 wherein, are carried out described method in multistep connection procedure.

19. methods according to claim 18, wherein, described multistep connection procedure Y shape configuration and and triangular configuration between convert.

20. methods according to claim 15, wherein, described power supply comprises three phase mains, and closed described direct solenoid is controlled contact site electric power is offered to three phase windings of described motor.